1. Field of the Invention
This invention relates to the field of apparatus and methods for creating sealed test chambers externally around pipe sections etc., the seals being that many thousands of psi pressure may be contained in the chambers.
2. Description of Prior Art
There exist substantial numbers of prior-art patents for apparatus wherein longitudinal and circumferential seals are provided in order to permit a sealed chamber to be defined around a section of pipe. Patents of this type include, for example, U.S. Pat. Nos. 2,255,921 and 3,744,822. However, the construction set forth in these and other patents are believed to be incapable of containing and sealing fluid pressures anywhere near as high as those which may be contained and sealed with the present apparatus, method and seals. It is to be understood that the higher the test pressure, the more readily and rapidly a leak may be detected.
It is extremely important that the apparatus be adapted to open and close rapidly, to laterally receive a pipe section when the apparatus is in open condition, and to seal a pressure of such extreme magnitude that even minute leaks will be readily apparent in a short test period.
Insofar as applicants are aware, the only prior-art external-tester apparatus which has achieved major commercial success in the oil-well industry is that described in U.S. Pat. No. 3,371,521, and improvements thereon which are specified in a notice of prior art filed in the present application file. Such apparatus is, however, deficient in important respects one of which is that it requires a unitarily-molded complex packer as shown in FIG. 9 thereof. The packer is such that the fluid in the test chamber only "sees" rubber, as stated in column 5 of such patent, starting at line 39. The packers of the type shown in FIG. 9 of U.S. Pat. No. 3,371,521 are not only complex and expensive to mold but also bulky to ship and store. Furthermore, when one portion of the packer wears out, the entire packer must be discarded, it being impractical or impossible to replace any worn portion of the packer. A further disadvantage relative to such packers is that they are sometimes difficult to load into the casings in the field, this being because (as set forth starting at line 75, column 6 of the patent) the as-molded packer circumference at its exterior is larger than the circumference of the closed casing at its interior.
It has long been thought impossible to create an external pipe tester which opens for lateral reception of the pipe and is capable of containing extremely high fluid pressures, yet is sealed by individual sealing elements which (a) are readily mass produced, shipped and stored, (b) are easily mounted in the casing in the field, (c) are individually replaceable when worn, and (d) may be made in small common molds.